Fix Timber to Metal Framing Part IV

The Finished Product
Using the special wing-tipped screws Merbau slatting was used as cladding over a metal framed gate. The gate frame was made from 30mm RHS steel tube with a 2mm wall thickness.  The gate post is a 50mm RHS steel tube with a 4mm wall thickness.  This shows how robust the drilling tip on the screws is as the gate post and mid post, another steel post, were no problem for driving these screws into.

Take a look for yourself and as always you are welcome to leave feedback or feel free to ask a question.

The blank canvas

The starting point for this garden gate makeover. The customer requirement was to fence this area off to keep a dog in. As an added bonus it would be good to keep the kids safe behind the gate because those stairs lead up to the road.

The finished gate and fence

The transformed walkway. If the gate seems narrow it is.  This was a custom designed arrangement and the gate frame itself is a whisker under 700mm wide.

Timber fixed with Wing Tipped
Self Drilling Self Tapping Screws

The screw heads all sit slightly below flush with the timber surface.  It takes a bit of practice to get it just right and a little driving each screw in, backing it out and driving it home again helps to get the right depth of countersink.

And from the back side it looks quite neat and tidy, save the haphazard wood pile.











Wing Tipped Screws. Just a small thing but they make a big difference.  Oh, and this gate and fence needed about 120 of them, plus a handful of ordinary timber screws for the end post which is timber screwed to the boundary fence.

Happy days.  Hope you found this article interesting.
Cheers,
Paul

Click to Return to Part I of this Series

Fix Timber to Metal Framing Part III

The Wing Tipped Marvel
Here's a picture of the beauty. This is the tool, as it should rightly be called, that makes fixing timber to steel framing a cinch.  And at around 10 cents a pop they're cheap as chips.

These screws have a drill-bit-like tip that cuts easily through timber closely followed by a pair of metal wings. The metal wings make the pilot hole bigger and provide relief so that when the screw is driven home the timber will not split.

When the screw tip drills through the mild steel frame, which they do remarkably easily, the wings shear off. The countersunk head is also fitted with a cutting face that self countersinks the head.

So, in a simple single operation the clever design of this screw drills a pilot hole, opens the pilot hole for relief, drills a pilot hole in the steel and using a self tapping thread cuts a grip into the steel and finishes it all off by countersinking it's own head!

Wonderful! It may seem obvious to some but to achieve the same result using a standard countersunk self tapping screw requires the following:

1. Predrill hole through timber and metal to the correct size for the self tapping screw.
2. Oversize the hole through the timber to stop the screw thread pulling directly on the timber.
3. Countersink the timber piece.
4. Drive the screw into position for a flush finish.

This operation requires about four times as much time as using the special wing tipped screws. One word of caution though.. remember the wings shear off once the screw drives through metal. As such, a screw cannot be re-used to make a complete new hole. The cutting heads on these screws will generally make several holes and in a pinch can be used in lieu of a drill bit, for example, to drill rivet holes!

In the last article of this series we take a quick peek at the finished result.

Click to Read Part IV

p.s. Working in Brissy? You can buy your screws from Russ-All Industrial.. the local bolt bloke on Pickering Street, Enoggera. No, sorry guys, Bunnings don't stock these pearlers!

Fix Timber to Metal Framing Part II

In the first article we looked at some basics of screw technology.  Next up we need some equipment to put them in.  The trusty handpowered screwdriver just will not do with our high-tech screws.

Drills

Self drilling screws are designed to be driven at about 1000 revs per minute (rpm).  

Most electric drills range between 1500 and 3000 rpm. An electric drill with a variable speed trigger can work, HOWEVER, be warned! An electric drill will not stop turning when you release the trigger like a cordless drill. This can make the job of driving screws quite dangerous. You've been warned.  Please be careful.

Cordless drills are usually the best device to drive screws; they run at the right speed and have adjustable torque settings. However, drilling through wood, into metal and countersinking the screw head is tough even for the toughest cordless drills.

The absolute best idea is to hire a Tec-Gun.  A Tec-Gun is an electric drill that only takes screwdriver bits (i.e. no drilling) runs at a close to optimum drive speed around 1200 rpm and has an electric brake.  That means when you let the trigger go the spindle stops turning.

Driver Bits

Just about anyone can and has used a cordless drill. 

The bits we're talking about (so you can ask for them at the hardware) are 6mm hexagonal driver bits.  These bits interchange easily with various heads, to suit various screw heads. You may be familiar with the Flat Head bit for a slotted head, a Phillips Head bit, sometimes called a cross point as well as some of the newer styles such as Torx and Pozi-Drive bits.

For the special wing-tipped self-drilling self-tapping screws we will be using we need a phillips head No.2 driver bit.  This is the most common size of phillips head bit in use today.

The reason for the different driver bits is that they are used for different purposes and generally the more complex patterns provide a more positive driving experience.  This means the bit is less likely to slip and damage the head.  It also makes their manufacture more expensive.

As an interesting aside, I recently bought a pack of outdoor timber screws made by Buildex that included a square driver bit! It seems ironic to me that we went from flat to cross to several variations of hexagonal design before coming back to a simple square.  And it actually drives long screws into hard wood exceptionally well.

Buying the right driver bits involves a little understanding. In the next article we are going to see just how easy it is to put some of this screw technology to good use.  For now we need to make sure we have the right tools.

Cheap bits are a waste of time and money, even though they look the same as expensive bits. Fancy coatings do help but in general good quality bits will advertise quality forging with an added bonus of a special shiny coating. For driving self-drilling, self-tapping screws into metal, buy the best driver bit you can get.  

As a rule, spend about five dollars per bit (c2011).  A five dollar bit will outlast at least five one dollar bits.  Then again, the odds are good you will break one or two so I'd suggest buying at least two good quality bits for the job you're about to undertake. 

For a good education, buy a cheap bit while you're there, no, get two! When you see in practice how long the cheap bits stand up to real work you will never waste your money again.

In Europe bits are graded according to quality.  Five star bits are the right temper with a high quality coating. Here in Australia we currently do not have such a grading system. The best idea is to try one or two bits from Bunnings (mid-range quality bits) and then track down your local tool stockist.  They can usually point you towards the quality you need for frustration free work.

Remember that the harder a metal is the more brittle it becomes.  Drilling into steel tube, through hard timbers like Merbau is a shocking series of stop/start drill work and your drill bit needs a bit of flexibility.  Inevitably though, even your best bits will succumb to breakage after a while.

Right!

Now we're armed with the right driver bit in our tec-gun we're ready to take a look at this modern wing-tipped marvel.

Click to Read Part III

Fix Timber to Metal Framing Part I

Building a gate or adding an attractive screen to your carport? Slatted timber finishes look great and with the right choice of screw can be assembled in no time.

In this four part article we are going to look at a modern marvel of screw technology that takes the hard work out of getting an accurate finish, fast.  First up, though, let's take a quick look at all things screwy!!

Screw That!

Screw technology has come along way from the earliest modern brass screws with a slotted head designed for wood. 

When we started working with metal, it quickly became apparent bolts and welding were both a cumbersome option for many applications.  Thus the self-tapping screw was developed.  This screw has a thread that points (narrows) toward the tip.  After drilling a pilot hole a self tapper will screw into metal.

However, as anyone who has used self tappers more than once, they don't always behave! If the metal you are screwing into is too thick the thread on the screw will often strip. Also, if the pilot hole is not big enough the screw just cannot get a grip. When the thread starts to bite the next challenge is to keep the head of the screw intact; damaging the head makes it virtually impossible to install properly and if it does go in can be a nightmare to remove, especially years later.

Moving right along the materials science boys came up with a screw hard enough to hold a point sharpened like a drill bit.  These screws will happily drill their own pilot hole, exactly the right size, and follow it in with a self-tapping thread to hold tight.

Now, the only practical method of using these self-drilling, self-tapping screws is with power. A cordless drill or a driver bit in a power-drill is just the ticket to successful installation of these screws.

Click to Read Part II